Catheters for the introduction or removal of fluids may be located in various venous locations and cavities throughout the body for the introduction or removal of fluids. Such catheterization may be performed by using a single catheter having multiple lumens. A typical example of a multiple lumen catheter is a dual lumen catheter in which one lumen introduces fluids and one lumen removes fluids. Catheterization may also be performed by using separate, individual single lumen catheters inserted through two different incisions into an area to be catheterized. Such multiple catheter assemblies are known as Tesio catheters.
Generally, to insert any catheter in a blood vessel, the vessel is identified by aspiration with a long hollow needle in accordance with the Seldinger technique. When blood enters a syringe attached to the needle, the syringe is disconnected and a thin guide wire is passed through the needle into the interior of the vessel. The needle is then removed leaving the guide wire within the vessel. The guide wire projects beyond the surface of the skin.
At this point, several options are available to a physician for catheter placement. The simplest is to pass a catheter into the vessel directly over a guide wire. The guide wire is then removed leaving the catheter in position within the vessel. However, this technique is only possible in cases where the catheter is of a relatively small diameter, made of a stiff material and not significantly larger than the guide wire, for example, for insertion of small diameter dual lumen catheters. If the catheter to be inserted is significantly larger than the guide wire, a dilator device is first passed over the guide wire to enlarge the hole. The catheter is then passed over the guide wire, and the guide wire and dilator are removed.
In the case of an individual, single-lumen catheter useful for insertion of multiple catheter assemblies (e.g., a Tesio catheter), a physician may use an introducer sheath. If a Tesio is used for hemodialysis, for example, each catheter is inserted in two separate veins, such as the femoral vein. Alternatively, each catheter is inserted in two different locations of the same vein, such as the internal jugular vein. The introducer sheath is simply a large, stiff thin-walled tube which serves as a temporary conduit for the permanent catheter which is being placed. The introducer sheath is positioned by placing a dilator device inside of the introducer and passing both the dilator and the introducer together into the vessel. A guide wire, left in the vessel after insertion by syringe as described above, and the dilator are then removed, leaving the thin-walled introducer sheath in place. The catheter is placed through the introducer sheath. Each of the catheters in the assembly is typically subcutaneously secured within the patient's body by subcutaneous tunnellings, or is externally affixed to the body.
The Tesio double catheter assembly while comfortable for the patient and very effective for hemodialysis still requires multiple procedures and incisions, thereby increasing the attendant risk of catheterization. However, the Tesio double catheter assembly provides the ability to independently insert and remove the catheters such that dialysis need not be unnecessarily prolonged.
To avoid double tunnelling procedures for Tesios, one recent catheter design provides a connected Tesio. The individual catheters are permanently linked in one portion by a retaining sleeve and distal ends are prespaced by an appropriate distance. The retaining sleeve fits snugly around the individual catheters. The sleeve is subcutaneously positioned below the incision site and outside the area to be catheterized. The sleeve renders the assembly self-retaining such that tunnelling is optional. While this device requires only one incision, it lacks the advantage of standard Tesios which are independently removable. Furthermore, if one individual catheter becomes clogged, develops a leak, or otherwise requires replacement, the entire double catheter assembly must be removed. If the patient is undergoing dialysis, the entire process must be stopped and a time-consuming and invasive surgical procedure must be performed to remove and replace the assembly in the manner of a multiple lumen catheter.
Dual lumen catheters are inserted through a single incision procedure. However, dual lumen catheters suffer from the same disadvantages as the Tesio double catheter assembly highlighted above in that one lumen cannot be replaced independently of the other lumen. Many dual lumen catheters also have poor flow characteristics due to the shape and size of the individual lumens.
Thus, there is a need in the art for a simple method of catheterization which is requires only one procedure, which takes advantage of the benefits provided by Tesio catheters, and which does not suffer from the shortcomings of the methods highlighted above. The present invention fills such a need.